The Hormone Cycle of a Contraction

Ok, lots of medical words coming your way but I will break everything down as much as I can! 💕

the onset of labor

1. Fetal stress stimulates the corticotropin hormone (ACH) by the antigrium pituitary gland (in your brain) which stimulates cortisol release (cortisol then releases).

   Many times we’re told that baby’s lungs secrete a hormone telling the parents body that it is ready for birth (aka air on the outside world). That until the body receives this signal, no birth will happen (unless it’s medically induced) which is one of the big reasons most people who are knowledgable regarding natural birth, say to wait until you go into labor on your own since no one really knows what is going on with baby.

2. Cortisol effects the placenta

   1. Decreases progesterone

   2. Decreases oestrogen

   3. Increases prostaglandins (uterine contractions and cervical ripener)

As baby’s head is pushed into the cervix (that is being ripened/softened by the prostaglandins) from the contractions/surges, it will then start the hormone loop process. But labor doesn’t fully kick off until there is a good amount of pressure on the cervix from baby’s head. So many times there will be a lot of Braxton Hick’s contractions or even irregular spaced contractions (early labor) until the hormone loop really gets a good momentum going.

established labor to birth

1. Uterus/Cervix stretch stimulates nerve fibers

2. Sensory fibers stimulate oxytocin from the posterior pituitary

   1. Oxytocin causes uterine contractions which stimulates prostaglandins

3. Repeat beginning at #4 until baby is born

What happens is baby’s head puts pressure on the uterus/cervix which in turn sends signals to the pituitary gland which then releases oxytocin (and prostaglandins, the cervical ripener/softener) which in turns produces more contractions/surges which pushes baby’s head into the cervix more which then starts the process all over again. It’s a loop that keeps happening until baby is born.

fourth stage

A similar process happens when the placenta is birthed, but the hormones typically come from baby suckling at the breast/chest and left overs from the actual birth. When people breast/chest feed it produces oxytocin when again, produce contractions/surges.

And even after the placenta is birthed, those contractions/surges will still happen when nipples are stimulated either by baby or pumping, and it is to return the uterus to its pre-pregnancy/gestational size.

does that make sense?

I hope that made sense! If you have any questions or comments (even if its because I got something wrong) please leave a comment on this blog! In doing research for this blog, it was difficult to find things human related for some reason as most of the research articles I was finding were about dogs (how fucking random is that 🙃).

It’s always nice to know what our bodies are doing, how they are doing it, and why they are doing it. And it always amazes me the intricate process that our bodies follow on their own.

Bodies are fucking magical ✨